Check out the video in this article. Shows that the allegation is totally bogus and utterly bullsh*t. Zero evidence of any 'assault' by Agüero in that video - after the steward pushes Sergio away forcefully he does appear to touch the guy but it is hardly classes as being 'struck' by the player.

The guy in the fluorescent jacket that rushes into the shot is a police evidence gatherer with a video camera. He will have been focused on the events on the ground but it may throw some light on matters

The steward should be ashamed of himself though. Pathetic attempt to get the City player into trouble. Probably a supporter of Bournemouth who has decided to wreak some retribution for the last minute goal.

"AFC Bournemouth are aware of an alleged incident which occurred following Manchester City’s second goal at Vitality Stadium on Saturday.
The club have been advised that due to a misunderstanding, an earlier statement alleging assault has been withdrawn and no assault took place.
AFC Bournemouth recognises that stewards and police were carrying out their duties in preventing encroachment onto the pitch, with the safety of players and supporters in mind.
The club will make no further comment on the matter."

Spot on Skoorb. Too late to stop the smearing of Aguero's and, by default, City's reputation though.
I would like to see that steward charged for wasting police time and to issue a public apology.
But, of course nothing of the sort will happen.

It gets worse for me in relation to the allegations made by the steward because of what happens prior to the incident with Sergio.

Watching the footage on MotD (from about 15 minuts into the programme) when they are discussing the incident. They show the melee looking out onto the pitch and you can see the steward later involved with Sergio in the midst of the fans, police and players. Large, blond haired guy wearing an orange tabard and initially facing the camera. There is a moment player's disengage and Fernandinho is moving away from the throng when that steward reaches out with his right arm, grabs the back of Fernandinho's shirt and drags him BACK into the crush. I have taken stills from the tv and will try and attach them but may have to do something to get them within the size limit if they won't upload.

Either way it is something which should be looked at by AFC Bournemouth.